Sealed keyboard

ABSTRACT

The invention relates to the sealing of a keyboard. The invention is particularly, but not exclusively, applicable in a keyboard fitted on an aircraft instrument panel. The keyboard comprises at least one switch, a rigid key allowing an operator to operate the switch, a front face comprising an opening traversed by the rigid key, and sealing means preventing particles from penetrating between the rigid key and the opening. According to the invention, the sealing means comprise a flexible membrane traversed by the rigid key, attached to the key and to the front face.

The invention relates to the sealing of a keyboard. The invention isparticularly, but not exclusively, applicable to a keyboard fitted on anaircraft instrument panel.

A keyboard usually has at least one switch surmounted by a rigid key. Anoperator presses on the top of the rigid key to operate the switch. Theswitch and the rigid key form mobile parts that are sensitive to thepenetration of solid or liquid particles likely to impair the operationof the keyboard. The presence of these particles requires maintenance ofthe keyboard either by cleaning or by changing the damaged mobile parts.To remedy this problem, improvements have been made to the sealing ofkeyboards by providing a flexible film either between the switch and therigid key, or above the rigid key. A keyboard usually comprises severalswitches each associated with a rigid key. The flexible film then coversall the switches or all the rigid keys. The flexibility of the film isnecessary to ensure that the film deforms during operations of theswitch or switches by an operator.

The deformation of the film has a disadvantage for the operator. Moreprecisely, the film introduces a flexible element between the finger ofthe operator and the switch. This flexible element adversely affects theprecision of control of the switch by the operator. For the operator, itis preferable to have only a rigid element between his finger and theswitch. If the flexible element is disposed between the switch and anassociated rigid key, the flexible element provides an additionalmovement of the rigid key when an operator presses on the key. The sameapplies to a flexible film covering the key. The finger of the operatorthen partially indents the flexible element. Precision of control of theswitch is, for example, necessary on an aircraft instrument panel. Thepilot using the keyboard of this instrument panel must be able to enterdata relating to the conduct of the aircraft with a perfect reliabilityand the presence of a flexible element reduces this reliability.

The object of the invention is to alleviate this fault by proposing akeyboard in which no flexible element is placed between the finger ofthe operator and the switch while ensuring a seal comparable to thatobtained with a continuous film covering the whole keyboard.

Accordingly, the subject of the invention is a keyboard comprising atleast one switch, a rigid key allowing an operator to operate theswitch, a front face comprising an opening traversed by the rigid key,and sealing means preventing particles from penetrating between therigid key and the opening, characterized in that the sealing meanscomprise a flexible membrane traversed by the rigid key, attached to thekey and to the front face.

It is well understood that the invention is not limited to a singleswitch surmounted by a rigid key. The invention is particularly wellsuited to a keyboard comprising a large number of switches eachsurmounted by a rigid key.

The invention will be better understood and other advantages will appearon reading the detailed description of an embodiment given as anexample, the description being illustrated by the attached drawing inwhich:

FIG. 1 shows an exemplary embodiment of a keyboard according to theinvention.

The keyboard shown in FIG. 1 comprises a switch 1 placed on a supportplate 2. The support plate 2 is, for example, a printed circuit boardproviding electrical connections necessary for the operation of theswitch 1. The support plate 2 may support several switches 1. Thekeyboard also comprises a rigid key 3 surmounting the switch 1, andallowing an operator to operate the switch 1. The material of the rigidkey 3 is selected to prevent any deformation of the key 3 when theoperator presses the key 3. The keyboard also comprises a front face 4comprising an opening 5 traversed by the rigid key 3. Sealing meansprevent particles situated on the outside of the keyboard, that is tosay where the operator is situated, from penetrating between the rigidkey 3 and the front face 4 via the space left free between the rigid key3 and the opening 5. These particles may consist of granules of dustpresent in the ambient air or of liquids likely to be spilt over thekeyboard by the operator.

The sealing means comprise a flexible membrane 6 traversed by the rigidkey 3. The flexible membrane 6 is attached both to the front face 4 andto the rigid key 3 advantageously by bonding.

Advantageously, keyboards comprise means of limiting the travel of therigid key 3 relative to the front face 4. More precisely, these meansare used to prevent too great a pressure of the operator on the rigidkey 3 from damaging the switch 1.

The limiting means comprise for example a shoulder 8 belonging to therigid key 3. The shoulder 8 forms a portion 9 of the rigid key 3, aportion that cannot penetrate inside the keyboard through the opening 5.The inside of the keyboard is the space lying between the support plate2 and the front face 4. The switch 1 is situated inside the keyboard.Thus, when the operator presses on the rigid key 3, it travels inwarduntil the shoulder 8 butts against the front face 4.

Advantageously, the shoulder 8 is used to attach the flexible membrane 6and the shoulder 8 comes into contact with the front face 4 via theflexible membrane 6, which softens a possible impact between the rigidkey 3 and the front face 4 when these two elements come into contactwith one another. Softening the impact is used to reduce the noise levelwhen the operator operates the keyboard. In FIG. 1, the travel of thekey is shown by reference C.

Advantageously, the rigid key 3 is transparent and the keyboardcomprises means of lighting the rigid key 3 from inside the keyboard.These lighting means comprise, for example, light emitting diodes 10attached to the support plate 2 inside the keyboard. The light emittingdiodes are, for example, powered by tracks printed on the support plate2.

The fact, thanks to the invention, that a continuous flexible filmcovering the whole keyboard is dispensed with allows the rigid key 3 tobe lit via the inside of the keyboard in the best conditions. Moreprecisely, thanks to the invention, the lighting passes through only onemedium other than the air, that is the rigid key 3. In the prior art,light rays had to pass through both the rigid key 3 and the flexiblefilm, which, as a consequence, had to be transparent. Thanks to theinvention, it is no longer necessary for the flexible film 6 to betransparent, which makes it possible to broaden the choice of thematerials of which it is made.

The top 11 of the rigid key 3 may be covered with an opaque materialsuch as for example paint, then the opaque material may be removedlocally, for example by engraving. The engraving may, for example, havethe shape of one or more alphanumeric characters. The lighting will thusbe used to view this or these characters.

1. A keyboard comprising; a switch, a rigid key allowing an operator to operate the switch, a front face having an opening traversed by the rigid key, and sealing means preventing particles from penetrating between the rigid key and the opening, wherein the sealing means comprise a flexible membrane traversed by the rigid key, attached to the key and to the front face.
 2. The keyboard as claimed in claim 1, wherein the flexible membrane is attached to the rigid key and to the front face by bonding.
 3. The keyboard as claimed in claim 1, wherein it comprises means of limiting the travel of the rigid key relative to the front face.
 4. The keyboard as claimed in claim 3, wherein the limitation means comprise a shoulder of the rigid key, and in that the shoulder is capable of butting against the front face when the operator presses on the rigid key.
 5. The keyboard as claimed in claim 4, wherein the flexible membrane is attached to the rigid key on the shoulder.
 6. The keyboard as claimed in claim 1, wherein it comprises means of lighting the rigid key via the inside of the keyboard, and in that the rigid key is transparent.
 7. The keyboard as claimed in claim 2, wherein it comprises means of limiting the travel of the rigid key relative to the front face.
 8. The keyboard as claimed in claim 2, wherein it comprises means of lighting the rigid key via the inside of the keyboard, and in that the rigid key is transparent.
 9. The keyboard as claimed in claim 3, wherein it comprises means of lighting the rigid key via the inside of the keyboard, and in that the rigid key is transparent.
 10. The keyboard as claimed in claim 4, wherein it comprises means of lighting the rigid key via the inside of the keyboard, and in that the rigid key is transparent.
 11. The keyboard as claimed in claim 5, wherein it comprises means of lighting the rigid key via the inside of the keyboard, and in that the rigid key is transparent. 